SOUTH SAN FRANCISCO, CA—It’s 9 am and Jed Guinto has just come home from work. Another 4 hours to rest and he goes to his second job. To make ends meet Guinto is working two full-time jobs in retail this year.

.

But federal tax tables that set the withholdings failed to account workers with more than one job, some married couples in which both spouses work, and some social recipients with jobs. Guinto could end up owing additional taxes when he files his tax return for 2009.